The present invention broadly relates to a new and improved apparatus for pressing the folded edges of folded paper products, especially printed products, which are conveyed by means of a conveyor.
Apparatuses for pressing the folded edges of folded printed products, especially of newspapers, have long been utilized in practice in the prior art. These apparatuses are designed such that the imbricated formation or flow of the printed products from the printing press arrive onto a belt or band conveyor. The folded edge of each newspaper or paper product forms the leading edge of each newspaper in the imbricated formation or product flow and overlaps a portion of the preceding newspaper or paper product. This imbricated product formation or flow is fed between one or more consecutive pairs of pressing cylinders or rollers. The folded edge of each product or newspaper thus is compressed or squeezed at the moment it passes through the gap of the individual pair of pressing cylinders or through the gaps of the plurality of pressing cylinders. The time duration elapsing during compression or squeezing of this folded edge is very short and the time duration decreases with increasing speed of conveyance of the imbricated product flow.
Paper, however, is a material which exhibits a certain resiliency or capability of recovering its shape. The very short time duration of the product compression or squeezing action of the known apparatuses is therefore not sufficient to compress the folded edges of the products in a permanent manner such that each product displays a minimum possible radius of curvature and especially can retain this minimum possible radius of curvature.
It will be understood that other apparatuses which are foreign to this type of equipment discussed previously are known for compressing the folded edges of newspapers. These known apparatuses neither compress the folded edge individually nor during conveyance of the paper products but instead press the folded edges while they are in a stack of folded paper products and especially during the formation of such a product stack. An example of such an apparatus is described in the German Patent Publication No. 2,822,029, which is substantially cognate to the Swiss Patent No. 618,399, and the U.S. Pat. No. 4,197,045, granted Apr. 8, 1980. The pressing or compression of the folded edges does not occur, as mentioned, during the passage or conveyance through the apparatus, i.e. during transportation of the paper products with these known apparatuses. The folded edges are not individually pressed, but to a certain degree are pressed collectively for all paper products already located in the product stack. Consequently, the folded edges of the paper products which are situated in the bottom or lower region of the product stack are possibly sufficiently pressed simply due to the inherent or dead weight of the paper products lying thereabove. In contrast, however, the folded edges of the paper products situated in the top or upper region of the product stack are usually not adequately pressed or compressed.